Method and system for the fast backup and transmission of data

ABSTRACT

In accordance with the present invention, the fastest possible one-to-one copying of data files which are to be backed up is performed from a source storage medium to a target storage medium. The data files include usable data and management data. After the copying, data held on the source storage medium is accessible to users during the backup. To perform the backup, a record table or synonym list provides access to the files which have been copied. From the record table, management data is temporarily replaced in order to meet access requirements for opening the copied data files at the target storage medium. The copied management data and useful data on the target storage medium remain unchanged. Advantageously, copied data files on the target storage medium can no longer be changed after copying and apart from the authorized backup program, no application can read the copied data files from the target storage medium.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates in general to a data processing systemand, in particular, to a method and system for fast backup andtransmission of data. Still more particularly, the present inventionrelates to a method and system for fast backup and transmission of datato ensure that the data cannot be altered.

2. Description of the Related Art

To protect data holdings from being lost, there is a need for a regularprocess in which the data is saved or backed up on a data storage media.This regular process of saving data is often referred to as performing a“backup”.

Because of the increasing volumes of data being stored and the moreinsistent demands for data security, the amount of data being backed upand the frequency of scheduled backups continues to increase in manysystems.

Conventionally, backups are performed at times other than the “on-linetimes”, such as at night, and the backed-up data is stored on magnetictape, magnetic disk, or other media at secure locations. In the event ofdata being lost, a user can retrieve data from the most recent backup inorder to keep the loss as small as possible.

In particular, backups are typically performed during the night shiftbecause the data must not change during a backup. A change in dataduring a backup typically causes synchronization problems. However, asthe volumes of data being backed up are becoming larger and larger, thenight is often not long enough to allow all the necessary data to bebacked up.

Given the demand for faster backup facilities, the InternationalBusiness Machines (IBM) RAMAC (Random Access Memory) Virtual Array (IBMRVA) magnetic disk storage system was developed which has an “IXFP(IBMExtended Facilities Product)/SnapShot™” function, referred to in whatfollows as “SnapShot”.

This SnapShot function allows entire disks to be copied in a very shorttime, e.g. from seconds to minutes. Once the disks have been copied,then on-line operation can start and all the backups can be made fromthe copies at any other time.

Details of the SnapShot function can be found in the technicalspecification relating to Snapshot. For the purposes of the presentinvention, it is desirable that copies of disks can be made in a veryshort time by a function such as Snapshot. Since the present inventionis not dependent on the SnapShot function as the only method of quicklycopying disks, the term “copied disks” will be used in the followingdescription to refer to “Snapshot” copies and other conceivable methodsof copying disks.

Copied disks as a basis for backups are disadvantageous in that after acopy is performed by SnapShot it may not be possible for variousdatabases and file systems which utilize particular methods of accessand identification, e.g. which rely on the source disk name, to befurther processed or saved. For this reason the fast copy performed bySnapShot cannot readily be used as a basis for backups by most operatingsystems.

Certain operating systems that are enabled to utilize copied disks as abasis for backups change the disk (i.e. volume) identification (referredto below as “VOLID”), thus avoiding “duplicate names”. This is themethod utilized by, for example, the IBM OS/390 operating system.However, this method of changing the disk VOLID only works because inthe OS/390 operating system the files are described or denoted by simplecatalogue structures.

In addition, while some operating system, such as OS/390, provide formaking changes to the VOLIDs during backups, there are certain crucialdrawbacks to making changes to the copied disks as a basis for backups.First, it is only possible to make changes to the copied disks if thereare no catalog structures denoting the files or if the catalogstructures which do denote them are simple. If the structures arecomplicated, errors may be caused by making changes to copied disks andthe process of making changes is time-consuming. Second, making changesto the copied disks goes against the normal backup philosophy bychanging a “frozen”, or unchanged, data holding at a later stage. Third,the data holdings on the amended disks could be changed by ordinaryapplications. Finally, the amended data cannot be copied straight backto the original source disk for disaster recovery. Therefore, it isgenerally safer for the copied disks to be left in the frozen state.

In particular, with reference to the figures, FIG. 1A-1C depictillustrative block diagrams of a conventional method for backing updata. First, FIG. 1A depicts copying the disks VOLID1 and VOLID2 by thefastest possible method (e.g. SnapShot). For simplicity's sake, the diskname (VOLID) is changed at the same time of the copy.

Next, as illustrated in FIG. 1B, the descriptors or identifiers of thefiles are adapted to the amended disk names in the appropriate databaseand file catalogs, as is currently performed by the IBM OS/390 operatingsystem. The process of adapting the descriptors or identifiers of thefiles to the amended disk names can be very complicated, utilizes asubstantial amount of time, and can lead to errors on the copied disks.

Thereafter, as depicted in FIG. 1C, the backup program can read thecopied disks and produce data backups. However, the method of the priorart is disadvantageous in that any applications can read from and writeto the copied disks, which is risky and undesirable.

An example of a Virtual Storage Extended/Enterprise Systems Architecture(VSE/ESA) installation operated by a fairly large user (a typical userof the SnapShot backup method) may contain 20 catalogs each covering 500files (including database systems) and 200 alternative indices,distributed over some 50 to 100 disks. The average is therefore 75 disksutilized for a backup. Also, paths to the alternative indices andnon-VSAM files are recorded. Therefore, the total number of disk changesinvolved in each backup is 12,640; giving a very clear picture of theamount of time involved in a backup and the risk of data being lost.

Another disadvantage of the prior art method, as depicted in FIG. 1C, isthat the amended disks cannot be copied back in the event of a loss fromthe original (source) disks without first being changed back to theoriginal disk identification.

Therefore, in view of the foregoing, it would be advantageous to providea method and system for backing up and transmitting data which ensuresthat the times taken by breaks for backing up or transmitting data areas short as possible and it is ensured that the copied data cannot bealtered.

SUMMARY OF THE INVENTION

In view of the foregoing, it is therefore an object of the presentinvention to provide an improved data processing system.

It is another object of the present invention to provide a method andsystem for fast backup and transmission of data.

It is yet another object of the present invention to provide a methodand system for fast backup and transmission of data to ensure that thedata cannot be altered.

In accordance with the present invention, the fastest possibleone-to-one copying of data files which are to be backed up is performedfrom a source storage medium to a target storage medium. The data filesinclude usable data and management data. After the copying, data held onthe source storage medium is accessible to users during the backup. Toperform the backup, a record table or synonym list provides access tothe files which have been copied. From the record table, management datais temporarily replaced in order to meet access requirements for openingthe copied data files at the target storage medium. The copiedmanagement data and useful data on the target storage medium remainunchanged. Advantageously, copied data files on the target storagemedium can no longer be changed after copying and apart from theauthorized backup program, no application can read the copied data filesfrom the target storage medium.

All objects, features, and advantages of the present invention willbecome apparent in the following detailed written description.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself however, as well as apreferred mode of use, further objects and advantages thereof, will bestbe understood by reference to the following detailed description of anillustrative embodiment when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1A-1C depict illustrative block diagrams of a prior artconventional method for backing up data;

FIGS. 2A-2B illustrate illustrative block diagrams of a preferredembodiment of the method for backing up data according to the presentinvention; and

FIG. 3 depicts a chart of a backup synonym list as employed in FIGS.2A-2B.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference now to the figures and in particular with reference toFIGS. 2A-2B, there is depicted illustrative block diagrams of apreferred embodiment of a method for backing up data according to thepresent invention.

In particular, the preferred embodiment illustrated in FIGS. 2A-2Bprovides a method for backing up data under the IBM VSE/ESA operatingsystem. The IBM VSE/ESA operating system is designed for mainframesemploying an S/390 architecture. The S/390 architecture is coming intoincreasingly widespread use as a server and database system fordistributed applications. Where there are large amounts of data there isalso a need for fast and regular backups of the data. Those skilled inthe art will appreciate, however, that the invention is not limited tomainframe architecture.

In utilizing the IBM VSE/ESA operating system, the vast bulk of the datais processed and stored by the “VSE/VSAM” access method (IBM VirtualStorage Extended/Virtual Access Method). The file handling is centeredon a group of catalogs which contain not data, but all the informationon the files (i.e. management information). The files themselves areonly accessible if required information can be made available from thecatalogs. Strict security standards are imposed in this case and, forexample, a check is always made to see whether the target disk has thesame name (VOLID) as was recorded in the catalog entry relating to thefile. Stringent checks are made the moment the catalogs are opened, e.g.the disk name has to be correct. The result of these checks is, forexample, that copied disks whose names are different do not tally withthe catalog entries. In addition, duplicated disk names are notpermitted (if they were, the disk name of the copy could be leftunaltered).

In particular, the present invention is suitable for making fast backupsfrom disks which have been copied (e.g. by SnapShot), without the copieddisks or their catalog entries being changed. As depicted in FIG. 2A, ina first step, a one-to-one copy is made of the data (useful data) whichis to be backed up or transmitted, including the data catalogs(management data). The copying is preferably carried out by the fastestpossible method, e.g. SnapShot. When the data is copied, the disk namesare changed from VOLID1 to disk name VOLIDX and disk name VOLID2 toVOLIDY. The copied data is stored either on the same disk or a differentdisk within the system.

Because the catalogs (the management data) only know the old disk names“VOLID1” and “VOLID2” and the data on a new disk has been copied with anew disk name, the files on disks “VOLIDX” and “VOLIDY” cannot beopened, read from or written to by any application.

As illustrated in FIG. 2B, immediately after the disks have been copied(e.g. by SnapShot) all the applications can begin their normalday-to-day transactions with the original disks “VOLID1” and “VOLID2”.

The data on the copied disks “VOLIDX” and “VOLIDY” is frozen because theinformation in the catalogs (management data) has not been adapted tothe new disk names and/or logic addresses. In addition, the files names,file name extensions, directory names, or the name of computers inparallel or distributed networks have not been adapted to the new disknames and therefore are frozen on the copied disks.

Via the synonym list that is stored in non-volatile memory and loadedinto volatile memory when the files are opened, the new backup programcan make backups from the data on the new disks “VOLIDX” and “VOLIDY” atany desired time and the same is true of transmitting data to anotherdata processing unit. The synonym list is either part of a backupprogram or else is separately available on a storage medium which thebackup program accesses while opening files. In particular, the synonymlist can be based on either the name function or the address function,depending on the nature of the operating system.

The temporary replacement by the synonym list takes place only in thevolatile memory of the data processing unit, thus ensuring that themanagement data and useful data cannot be changed on the new disks“VOLIDX” and VOLIDY” when the files are opened. In addition, the backupprogram performs only a read function when opening the files.

In particular, in utilizing the method of backing up data according tothe present invention, the VSE/VSAM file opening in the IBM VSE/ESAoperating system is advantageously performed with the help of a synonymlist. Internally in the IBM VSE/ESA operating system, a small interfaceis set up which detects that synonym backup is being utilized and thatthere is a synonym list present. According to entries of the synonymlist, the catalog and file accesses required are diverted to the diskswhich have been copied (e.g. by SnapShot). It is important in thisconnection for the identifications of the files to be backed up toinclude not only their file names but also the disk name (VOLID) and thecatalog name.

Referring now to FIG. 3, there is depicted a chart of a backup synonymlist as employed in FIGS. 2A-2B. An element of the present invention isa table or so-called synonym list. The disk names or other identifierswhich are needed are stored in this synonym list as pairs. Each originaldisk name has a fixed synonym name assigned to the original disk name;where other identifiers are used, the original identifier has a fixedsynonym identifier assigned in the same way. The synonym list is eitherpart of the data backup program or else is stored on a storage mediumseparately from the data backup program.

The files in question on the copied disks are not accessible to a normalapplication because the identifier or catalog entry does not fit, or inother words has not been adapted to the new disk. Therefore, aninterface (hook) has to be incorporated in the relevant operating systemwhich will detect the presence of the synonym list and will analyze itscontents. This interface is simple and will typically be simpler than asubroutine which changes all the identifiers on the copied disks. Thedifficulties caused by having the identifiers changed by a subroutineare described in connection with the prior art.

In particular, one advantage of the method according to the presentinvention is that data holdings can no longer be changed after copying(they are “frozen” ). In addition, it is advantageous that apart fromthe authorized backup program, no application can change the data (thedata is secure). Moreover, it is advantageous that even a considerabletime later, the data held on a copied disk can still be used as areplacement for data which is actively being produced because the datawhich is held is clearly defined by the time of the copy (disasterrecovery).

As depicted in FIG. 3, the synonym list for IBM VSE/ESA operating systemcontains source and target information. “SOURCE” (original storagemedium) here means the point of departure or, in other words, thecatalog of and disks forming the original storage medium, while “TARGET”(target storage medium) here means the target storage medium for thefast copy (e.g. made by SnapShot) including its catalog.

First, a copy of the disks is made. In particular, not all data on adisk needs to be copied at each backup, but a copy of only that datawhich has been altered or added since the last backup may be made. Thedata actively being produced on the source disks can be processed assoon as the copying has been completed.

The subsequent steps of the method for producing a backup can take placein parallel or in order with the processing of the active data:

1. A catalog synonym name must be loaded into the main catalog. The maincatalog contains information on the names and disk names (addresses) ofthe data catalogs. The newly inserted catalog synonym points to theaddress of the copied catalog (disk address). This function ispreferably performed by the “Import Connect” function which is part ofthe “IDCAMS” sub-routine of the VSE/ESA operating system. Anotherpossibility would be for this functionality to be included in the backupprogram.

2. Via the main catalog, the backup program opens the copied catalog sothat the backup program can obtain from the data in the copied catalogall the information on the files and the data contained in them. Forthis access, the synonym list is utilized so that the different names inthe catalog, which would cause access to be refused, can be temporarilyreplaced.

3. With the help of the synonym list, the backup program opens all thefiles in the same way as it does the catalog by temporarily replacingthe different disk names. The temporary replacement by the synonym listtakes place only in the volatile memory of the data-processing unit,thus ensuring that the management data and useful data cannot be changedon the new disks “VOLIDX” and VOLIDY” when the files are opened. All thefiles having been opened with the help of the synonym list, it isensured that the files or data on the copied disks (target disks) canonly be read by the backup program.

4. The data in the files can now be read in the conventional manner andwritten to a backup storage medium.

Therefore, the synonym list ensures that access is possible to thecopied data, changed to the source data are prevented, and backup cantake place in parallel with the processing of the source data. Inaddition, the backup process can be standardized, i.e. the synonym listneed not be constantly amended because backup jobs will be run every dayor every night on the same files.

The following example shows the job control notation under IBM VSE/ESA:

// JOB BACKUP VSAM FILES from Snap Volumes // ASSGN SYS005, 180 // DLBLIJSYSUC, ‘VSESP.SNAP.CATALOG’,,VSAM // EXEC IDCAMS, SIZE=AUTO /* SynonymName for the snapped Catalog */ - IMPORT CONNECTOBJECTS((VSESP.SNAP.CATALOG - VOLUMES (VOL-X) DEVT(3390))) -CATALOG(MASTER.CATALOG) /* Backup from IXFP/SnapShot volumes */ - BACKUP(*) - SYNLIST - SOURCEVOLUMES(VOL-1, VOL-2) - TARGETVOLUMES(VOL-X,VOL-Y) - CATALOG(VSESP.USER.CATALOG) - SYNCATALOG(VSESP.SNAP.CATALOG) /*/&

With the example, certain new backup parameters have been introduced:

SYNLIST indicates that “synonym backup” is being utilized and that thereis a synonym list present.

SOURCEVOLUME(..) designates the group of source disks. The designatedgroup of source disks are the producing disks.

TARGETVOLUMES(..) designates the target disks. It is to these targetdisks that the files and catalogs are copied. The source and targetdisks are considered to be pairs, positionally speaking.

CATALOG(..) designates the catalog relating to the source data.

SYNCATALOG(..) designates the synonym name of the copied catalog.

It is important to note that, although the present invention has beendescribed in the context of a fully functional computer system, thoseskilled in the art will appreciate that the mechanisms of the presentinvention are capable of being distributed as a program product in avariety of forms, and that the present invention applies equallyregardless of the particular type of signal-bearing media utilized toactually carry out the distribution. Examples of signal-bearing mediainclude, but are not limited to, recordable-type media such as floppydisks or CD-ROMs and transmission-type media such as analogue or digitalcommunications links.

While the invention has been particularly shown and described withreference to a preferred embodiment, it will be understood by thoseskilled in the art that various changes in form and detail may be madetherein without departing from the spirit and scope of the invention.

What is claimed is:
 1. A system for backup of data files, said systemcomprising: a source storage medium having a source storage mediumidentifier, said source storage medium comprising a plurality of datafiles, wherein said plurality of data files comprise management data; atarget storage medium to which said plurality of data files are copied,said target storage medium having a target storage medium identifierthat is different from said source storage medium identifier; means forupdating a record matching said source storage medium with said targetstorage medium; means for loading said record into a volatile memory ofa data processing system in order to temporarily replace said managementdata at said target storage medium with said information from saidrecord, in response to a request to backup said plurality of copied datafiles from said target storage medium to a backup storage medium; andmeans for temporarily replacing said management data at said targetstorage medium with information from said record in order to meet accessrequirements for opening said plurality of data files at said targetstorage medium, such that said opened plurality of data files areenabled for transmittal to said backup storage medium.
 2. The system forbackup of data files according to claim 1, said system furthercomprising: means for copying said plurality of data files from saidsource storage medium to said target storage medium.
 3. The system forbackup of data files according to claim 1, wherein said source storagemedium and said target storage medium are included in a data processingsystem.
 4. The system for backup of data files according to claim 1,wherein said source storage medium and said target storage medium arephysically separate storage media.
 5. The system for backup of datafiles according to claim 1, wherein said source storage medium and saidtarget storage medium form are physically a single storage media.
 6. Thesystem for backup of data files according to claim 1, wherein said meansfor temporarily replacing said management data at said target storagemedium with information from said record further comprises: means forsearching for directory information in said management data at saidtarget storage medium which does not meet access requirements foropening said plurality of copied data files from said target storagemedium; and means for temporarily replacing said directory informationwhich does not meet said access requirements with said information fromsaid record in order to meet said access requirements and enable openingof said plurality of copied data files for transmittal to said backupstorage medium.
 7. The system for backup of data files according toclaim 6, said means for searching for directory information in saidmanagement data at said target storage medium which does not meet accessrequirements for opening said plurality of copied data files from saidtarget storage medium further comprising: means for searching for a nameof said source storage medium.
 8. The system for backup of data filesaccording to claim 6, said means for searching for directory informationin said management data at said target storage medium which does notmeet access requirements for opening said plurality of copied data filesfrom said target storage medium further comprising: means for searchingfor a logic address of said source storage medium.
 9. The system forbackup of data files according to claim 1, said means for updating arecord matching said source storage medium with said target storagemedium, further comprising: means for storing said record in anon-volatile memory of said data processing system.
 10. The system forbackup of data files according to claim 1, said means for temporarilyreplacing said management data at said target storage medium withinformation from said record, further comprising: means for temporarilyreplacing said management data at said target storage medium in saidvolatile memory of said data processing system, such that said pluralityof copied data files are opened unchanged from said target storagemedium.
 11. The system for backup of data files according to claim 1,said system further comprising: means for enabling only a backup programcomprising said record to read said plurality of copied data files fromsaid target storage medium.
 12. The system for backup of data filesaccording to claim 1, said system further comprising: means for changinga name of said target storage medium when copying said plurality of datafiles from said source storage medium to said target storage medium. 13.The system for backup of data files according to claim 1, wherein saidplurality of data files comprise management data and useful data.
 14. Amethod for automatic backup of data files, said method comprising thestep of: copying a plurality of data files from a source storage mediumto a target storage medium, said source storage medium and said targetstorage medium having different identifiers, wherein said plurality ofdata files comprises management data; updating a record matching saidsource storage medium with said target storage medium; loading saidrecord into a volatile memory of a data processing system in order totemporarily replace said management data at said target storage mediumwith said information from said record, in response to a request tobackup said plurality of copied data files from said target storagemedium to a backup storage medium; and temporarily replacing saidmanagement data at said target storage medium with information from saidrecord, such that access requirements for opening said plurality of datafiles are met from said record in order to enable transmittal of saidplurality of data files from said target storage medium to said backupstorage medium.
 15. The method for automatic backup of data filesaccording to claim 14, wherein said step of temporarily replacing saidmanagement data at said target storage medium with information from saidrecord further comprises the steps of: searching for directoryinformation in said management data at said target storage medium whichdoes not meet access requirements for opening said plurality of copieddata files from said target storage medium; and temporarily replacingsaid directory information which does not meet said access requirementswith said information from said record in order to meet said accessrequirements and enable opening of said plurality of copied data filesfor transmittal to said backup storage medium.
 16. The method forautomatic backup of files according to claim 15, said step of searchingfor directory information in said management data at said target storagemedium which does not meet access requirements for opening saidplurality of copied data files from said target storage medium furthercomprising the step of: searching for a name of said source storagemedium.
 17. The method for automatic backup of files according to claim15, said step of searching for directory information in said managementdata at said target storage medium which does not meet accessrequirements for opening said plurality of copied data files from saidtarget storage medium further comprising the step of: searching for alogic address of said source storage medium.
 18. The method forautomatic backup of files according to claim 14, said step of updating arecord matching said source storage medium with said target storagemedium, further comprising the step of: storing said record in anon-volatile memory of said data processing system.
 19. The method forautomatic backup of files according to claim 14, said step oftemporarily replacing said management data at said target storage mediumwith information from said record, further comprising the step of:temporarily replacing said management data at said target storage mediumin said volatile memory of said data processing system, such that saidplurality of copied data files are opened unchanged from said targetstorage medium.
 20. The method for automatic backup of files accordingto claim 14, said method further comprising the step of: enabling only abackup program comprising said record to read said plurality of copieddata files from said target storage medium.
 21. The method for automaticbackup of files according to claim 14, said method further comprisingthe step of: changing a name of said target storage medium when copyingsaid plurality of data files from said source storage medium to saidtarget storage medium.
 22. The method for automatic backup of filesaccording to claim 14, said step of copying a plurality of data filesfrom a source storage medium to a target storage medium, furthercomprising the step of: copying a plurality of data files wherein saidplurality of data files comprise said management data and useful data.23. A computer program product to provide backup of data files, saidprogram product comprising: a storage medium; and program instructionson said storage medium for: copying a plurality of data files from asource storage medium to a target storage medium, said source storagemedium and said target storage medium having different identifiers,wherein said plurality of data files comprise management data; updatinga record matching said source storage medium with said target storagemedium; loading said record into a volatile memory of a data processingsystem in order to temporarily replace said management data at saidtarget storage medium with said information from said record, inresponse to a request to backup said plurality of copied data files fromsaid target storage medium to a backup storage medium; and temporarilyreplacing said management data at said target storage medium withininformation from said record, such that access requirements for openingsaid plurality of data files are met in order to enable transmittal ofsaid plurality of data files from said target storage medium to saidbackup storage medium.
 24. The computer program product according toclaim 23, wherein said program instructions for temporarily replacingsaid management data at said target storage medium with information fromsaid record further include program instructions for: searching fordirectory information in said management data at said target storagemedium which does not meet access requirements for opening saidplurality of copied data files from said target storage medium; andtemporarily replacing said directory information which does not meetsaid access requirements with said information from said record in orderto meet said access requirements and enable opening of said plurality ofcopied data files for transmittal to said backup storage medium.
 25. Thecomputer program product according to claim 24, wherein said programinstructions for searching for directory information in said managementdata at said target storage medium which does not meet accessrequirements for opening said plurality of copied data files from saidtarget storage medium further comprise program instructions for:searching for a name of said source storage medium.
 26. The computerprogram product according to claim 24, wherein said program instructionsfor searching for directory information in said management data at saidtarget storage medium which does not meet access requirements foropening said plurality of copied data files from said target storagemedium further comprise program instructions for: searching for a logicaddress of said source storage medium.
 27. The computer program productaccording to claim 23, wherein said program instructions for updating arecord matching said source storage medium with said target storagemedium, further comprise program instructions for: storing said recordin a non-volatile memory of said data processing system.
 28. Thecomputer program product according to claim 23, said programinstructions for temporarily replacing said management data at saidtarget storage medium with information from said record, furthercomprising program instructions for: temporarily replacing saidmanagement data at said target storage medium in said volatile memory ofsaid data processing system, such that said plurality of copied datafiles are opened unchanged from said target storage medium.
 29. Thecomputer program product according to claim 23, further comprisingprogram instructions for: enabling only a backup program comprising saidrecord to read said plurality of copied data files from said targetstorage medium.
 30. The computer program product according to claim 23,further comprising program instructions for: changing a name of saidtarget storage medium when copying said plurality of data files fromsaid source storage medium to said target storage medium.